Radial compressors or turbines



July 2, 1957 w. T. VON DER NUELL 2,797,858

RADIAL COMPRESSORS OR TURBINES Filed March 22, 1954 F/'g./.

2o W I 24 .8 ///1 I I4 I5 ERNER I V0 BY $4 #7 M l l l l United Statessee RADIAL COMPRESORS OR TURBINES Werner '1. von der Nuell, SantaMonica, Calif., assignor to The Garrett Corporation, Los Angeles, Calif,a corporation of California Application March 22, 1954, Serial No. 417,847

Claims. (Cl. 230-114) The present invention relates to radialcompressors or turbines, and more particularly to means for effectingefficient energy distribution over the surface of the rotor blades ofsuch machinery and adapted for use as a diffuser arrangement for aradial compressor, or as a nozzle structure for a radial turbine whenoperating with compressible fluids moving at high Mach numbers.

The radial clearance between the blades of a wheel and vanes adjacentthe periphery thereof influences the performance characteristics of thewheel whether it be used as a turbine, compressor, or fluid pump. Duringoperation of a conventional variable area nozzle adjacent a bladedwheel, radial clearance of the vanes relative to the wheel bladesincreases or decreases according to angular adjustment thereof. Suchprogressive increase in vane, or nozzle clearance adjacent the peripheryof a bladed Wheel may reduce the efliciency thereof when operating at anangular position different from the originally designed position, andtherefore it limits the practical range within which nozzles or vanesmay be angularly adjusted.

According to the present invention, and in order to accomplishsubstantially equal energy distribution on the surfaces of wheel blades,the blade extremities are disposed at an angle to the axis of the wheel,whereby they describe a frusto-conical path when the wheel rotates. Aplurality of nozzles are arranged in conforming angular relation to thewheel blade extremities. The pivotal axis of each nozzle or vaneintersects the angularly disposed edges thereof at or near a medianpoint thereon, whereby pivotal movement of each vane about its axiscauses a portion of said angularly disposed edge to move toward theconforming edges of the wheel blades while another portion of saidangularly disposed edge moves away therefrom. in this manner asubstantially constant mean clearance may be maintained betweenco-operating edges of nozzles or vanes and wheel blades throughout aconsiderable range of adjustment or load changing variation thereofwhereby substantially equal fluid energy distribution on the wheelblades is maintained during pivotal adjustment of the vanes.

An object of the invention is to provide means for effecting efi'lcientfluid energy distribution over surfaces of compressor or turbine wheelblades when operating with compressible fluids moving at high Machnumbers.

Another object of the invention is to provide vane means which, whenoperated throughout a wide range of area adjustment, will maintain asubstantialy constant mean clearance with respect to peripheral portionsof a bladed wheel.

A further object of the invention is to provide means which may beemployed in either turbines or compressors for maintaining 'efliciencythereof throughout a considerable range of flow variation.

Another object of the invention is to provide means which permitsreduction of the disc shroud diameter of a bladed wheel, therebyreducing the centrifugal stress level therein in operation.

A further object of the invention is to provide means for maintainingsubstantially constant mean clearance of variable vanes with a bladedwheel which is simple and economical to produce in proportion to itsfunction and yet very efficient and durable in operation.

Other objects and advantages of the invention may be apparent from thefollowing specification, claims, and drawing of this application, inwhich:

Fig. 1 is a fragmentary axial sectional view of a bladed wheel andvariable vane structure according to the present invention; and

Fig. 2 is a fragmentary perspective view of a bladed wheel having aplurality of co-operating vanes constructed according to the presentinvention.

A wheel 10 is substantially conventional in construction and isgenerally of the radial type, being useful either in a centrifugalcompressor or a centripetal turbine. This wheel is provided with blades11 having radially extending portions terminating in outer edge portions12 which are disposed at an angle to the axis 13 of the wheel 10. Theedges 12 of the blades 11 converge toward the axis 13 of the wheel.Thence, the blades at said edges 12 form the periphery of the wheelwhich when rotating describes a frusto-conical surface of revolutionadjacent to which vanes 14 are positioned. The angle of the edges 12,with respect to the axis of the wheel, provides for substantially equalflow path lengths, through the wheel, adjacent wheel shroud 24 andstationary or casing shroud 25. This arrangement provides for more evenloading of the overall area of the blades and thereby renders the wheelmore efficient when operating, to either extract energy from, or addenergy to, a compressible fluid.

The vanes 14 are provided with edges 15 substantially parallel to andconforming angularly with the edges 12 of the turbine wheel blades 11.The vanes 14 at their edges 16 and 17 are confined by passage walls 18and 19. Each vane 14 is provided with a trunnion 20 axially parallelwith the wheel axis 13. The axis 21 of each vane 14 intersects the edges12 and 15 of the wheel blades 11 and vanes 14 respectively near themedian point 22 lying between the limits of said edges 12 and 15. Underideal conditions the median point 22 should be half way between theextremities of these edges but, due to certain mechanicalconsiderations, may vary so that the median point 22 may not be half waybetween the limits of the co-operating wheel blade and vane edges. Whenthe wheel 10 is constructed as shown in Fig. 1 wherein the wheel bladeand vane edges are directed at the angle as shown, the periphery 23 ofthe shroud disc portion 24 of the wheel 10 may be relatively small inproportion to the overall periphery of the wheel at the outerextremities of the blades thereof. Such diametrical proportions permitthe back disc 24 of the wheel 10 to be operated with relatively lightcentrifugal loading in proportion to the speed-diameter ratio of thewheel.

The operation of the wheel and vane structure of the present inventionis substantially as follows.

Whether the wheel 10 is rotating and being operated as a pumping wheelor whether 'it is driven as a turbine by gas directed through the vanes14, the adjustable operation of the vanes with respect to the peripheraledges of the wheel blades is substantially the same. In order to varyblade loading or diffusion of fluid therefrom the vanes 14 may bepivoted about their axes 21 whereby their edge portions 15 extendinginwardly of each axis 21 will be caused to move away from the edges 12of the wheel blades, while the portions of the edges 15 outwardly of theaxis 21 will be caused to move toward the edges 12 of the wheel blades.In this manner a substantially constant mean clearance of the vane andco-operating blade edges may be maintained throughout a considerablerange of angular adjustment of the vanes relative to the wheel.

The degree of angularity of the vane edges 15 with respect to the axis13 of the wheel may be varied in proportion to the desired pivotal angleof the vanes 14 about the axes 21 thereof. Furthermore, such a degree ofangularity may be varied for other design considerations as may benecessary. With this arrangement substantially equal clearance existsbetween the vanes and the wheel blades near both shrouds 24 and 25.Since fluid flow path lengths through the wheel between the blades andalong the shrouds 24 and 25 may be made more nearly equal, aco-operative relationship exists between vane-to-blade clearance andfluid energy distribution on the blades. It will be understood thatblade loading varies with the varying wheel radii along the shrouds 24and 25 and hence only approximate equalization of energy distributionthroughout the surfaces of the blades will usually be accomplished. Thissubstantial uniformity of energy distribution is adequate and of greatbenetion when rotating, a plurality of adjustable vanes having edgesspaced from and substantially parallel to said outer edges of saidblades, and means supporting said vanes for pivotal movement about axeswhich intersect said frusto-conical surface of revolution at a medianlocation with respect to the limits of the outer edges of said blades.

2. An energy distributing mechanism arranged to maintain substantiallyconstant mean clearance between variable vanes and the peripheralportions of a bladed wheel, I comprising: a bladed wheel having bladesextending between the axis and the periphery thereof, said blades havingouter edges which are angularly disposed to the axis of said wheelwhereby said edges describe a general frusto-conical surface ofrevolution when rotating, a plurality of variable vanes having edgesspaced from and substantially parallel to said outer edges of saidblades,

and means supporting said vanes for pivotal movement about axes whichintersect said frusto-conical surface of J revolution at a locationbetween the limits of the outer edges of said blades.

3. In a mechanism for effecting eflicient fluid energy distribution oversurfaces of a bladed wheel, said bladed wheel having blades extendingbetween the axis and the periphery thereof, said blades having outeredges which are angularly disposed to the axis of said wheel wherebythey describe a generally frusto-conical surface of revolution whenrotating, a plurality of variable vanes having 1 edges substantiallyconforming to the outer edges of said blades, and means supporting saidvanes for pivotal movement about axes which intersect saidfrusto-conical surface of revolution at a location between the limits ofthe outer edges of said blades.

4. In a mechanism for effecting efiicient fluid energy 7 distributionover surfaces of a bladed wheel, said bladed wheel having bladesextending between the axis and the periphery thereof, said blades havingouter edges which I are angularly disposed to the axis of said wheelwhereby they describe a generally frusto-conical surface of revolutionwhen rotating, a plurality of variable vanes having edges substantiallyconforming to the outer edges of said blades, and means supporting saidvanes for pivotal movement about axes which intersect saidfrusto-conical surface of revolution at a location between the limits of4 the outer edges of said blades, and a shroud on said wheel to whichsaid blades are fixed, said shroud being of lesser diameter than themajor diameter of said frusto-conical surface of revolution.

5. Mechanism for effecting efficient fluid energy distribution oversurfaces of a bladed wheel, said bladed wheel having blades extendingbetween the axis and the periphery thereof, said blades having outeredges which are angularly disposed to the axis of said wheel wherebythey describe a generally frusto-conical surface of revolution whenrotating, a plurality of variable vanes having edges substantiallyconforming to the outer edges of said blades, means supporting saidvanes for pivotal movement about axes which intersect saidfrusto-conical surface of revolution at a location between the limits ofthe outer edges of said blades, the pivotal axes of said vanes beingsubstantially parallel to the axis of said wheel.

6. In a mechanism for effecting efficient fluid energy distribution oversurfaces of a bladed wheel, a wheel provided with blades includingsubstantially radially disposed portions having outer edges forming theperiphery of the wheel, the outer edges of said blades being disposed ingenerally converging relationship with the axis of said wheel, variablevanes having inner edges conforming with the outer edges of said blades,and means supporting said variable vanes for pivotal movement about axesintersecting said inner and outer edges at a location between the limitsthereof.

7. In a mechanism for effecting eflicient fluid energy distribution oversurfaces of a bladed wheel, a wheel provided with blades includingsubstantially radially disposed portions having outer edges forming theperiphery of the wheel, the outer edges of said blades being disposed inconverging relationship with the axis of said wheel, variable vaneshaving inner edges conforming with the outer edges of said blades, meanssupporting said variable vanes for pivotal movement about axesintersecting said inner and outer edges at a location between the limitsthereof, and a shroud on said wheel to which said blades are fixed, saidshroud being of lesser diameter than the periphery of said wheel at theouter edges of said blades.

8. In a mechanism for effecting eflicient fluid energy distribution oversurfaces of a bladed wheel, a wheel provided with blades includingsubstantially radially disposed portions having outer edges forming theperiphery of the wheel, the outer edges of said blades being disposed inconverging relationship with the axis of said wheel, variable vaneshaving inner edges conforming with the outer edges of said blades, meanssupporting said variable vanes for pivotal movement about axesintersecting said inner and outer edges at a location between the limitsthereof, and a shroud on said wheel to which said blades are fixed, saidshroud being of lesser diameter than the periphery of said wheel at theouter edges of said blades, the pivotal axes of said vanes beingsubstantially parallel to the axis of said wheel.

: supported in said chamber for rotation about the axis thereof, saidwheel having blades extending between the central region and theperiphery thereof, the outer ends of said blades terminating in edgesdisposed at an angle to the axis of said wheel; a plurality of diffuservanes disposed in said passage, said vanes having edges substantiallyparallel to and spaced from the edges of said blades; and meanspivotally supporting said vanes for adjustment about axes intersectingthe angularly disposed edges of said blades.

10. In an elastic fluid mechanism, a casing forming a wheel chamberhaving passages communicating axially and peripherally therewith, thelatter passage being substantially normal to the axis of said wheelchamber; a wheel supported in said chamber for rotation about the axisthereof, said wheel having blades forming passages communicating atopposite ends with the axial and peripheral passages in said casing,said blades terminating at the periphery of said wheel in planesdisposed in angular relationship with the axis of said wheel; aplurality of diffuser vanes disposed in the passage at the periphery ofsaid chamber, said vanes having edges parallel to and spaced from theangular edges of said blades; and pivot means extending substantiallyparallel to the axis of said Wheel, said pivot means supporting saidvanes for adjustment about axes extending through the angular edges ofsaid blades.

References Cited in the file of this patent UNITED STATES PATENTS

